Hi all

Thanks to all respondents to original thread.
Have shifted emphasis here so new thread in order.

My concern is pump over!
As roughly outlined in my previous thread, the solenoid valve for heating is
half way between ground and first floor, with upstairs feed to all rads in
15mm pipe from this point.
The feed to the cylinder and vent is 22mm with the solenoid close to the
cylinder on the first floor.
On advice from previous thread, I tried to "force" flow to 2 upstairs rads
by turning all downstairs rads off (this is a likely scenario if all trvs
close doownstairs).
I didn't get as far as checking these 2 rads because water started to pump
over into the header tank immediately, even with the upstairs bathroom rad
fully open (both lockshield and control valves).

My dilemma is that it appears pump over is inevitable with this piping.
With downstairs rads off, the pump runs and is faced with 2 routes, either
22mm up passed cylinder and over to header tank, or 15mm with fittings and
rad valve resistance.
Surely, as installed, this arrangement will always pump over rather than
feeding the upstairs rads?

I have two theories:

1. The systems were never designed to have trvs, therefore some down stairs
flow would always avoid the pump over.
2. There is a problem with the heating solenoid valve (although it seems to
work OK) and it is presenting some restriction. So add the further
restriction of only 15mm pipe available and pump over occurs.


Anyone shed any further light on this please?


TIA

Phil